This pulled tape off the take-up reel as well as off the supply reel and damaged the tape transport because the tension arms were suddenly released when the tape came off the takeup reel.A small amount of material was transferred from many aged tapes to the tape transport, even from tapes that were read successfully. These deposits were most conspicuous on the read and write heads but also were found at other 6 places along the tape path, particularly on the urethane rubber-coated capstan.A swab soaked in ethanol was used to clean the read and write heads after each piece of tape was tested and the whole tape path was cleaned after about ten tapes had been tested.Subsequent to the reading test, pieces were cut from an end of the tape for measurement of peel force and rolls and elongation for separation. Tapes that had been read successfully were reequilibrated as above, reweighed, and aged for another period.
Peel Force MeasurementsThe adhesion of the binder layer to the PET support was measured by a somewhat different method than described in the previous report. bears against the non-magnetic side of the tape, so tackiness of the back coating is disastrous. Such tackiness was noticed when the tapes were loaded onto reels before the reading test because adjacent layers of the tape did not slide over one another. Other tapes have behaved somewhat similarly on a few occasions but they only followed the capstan part way around and then peeled off with an abrupt snap. Degradation products may have moved from the magnetic side to the back side of the adjacent layer making such tapes marginally tacky.
Attempts to Rejuvenate TapeOne tape that failed after slight progress into the data block was completely read ten times after it had been hand wound so all of the data area had passed over the read and write heads, which were then cleaned. A substantial deposit had accumulated on the read and write heads. Wiping another failed tape with an alcohol soaked swab did not make it readable.Presumably the swab should also have removed deposits from the tape.About ten attempts were made to rejuvenate failed tapes by aging them at 85 and 60°C over a desiccant. Only one such tape became readable.
Lifetime EstimatesTape lifetime, defined as the aging time associated with failure to be readable for 10 passes, lies in the interval between the end of the aging period at which a piece of tape was read ten times and the end of the subsequent aging period after which it could not be read ten times. Figure 9-18 show these intervals for aging at 85 and 60°C as horizontal bars, the ends of which show the interval described above. Results with other measured quantities 2% at 50% RH.Larger differences occur at higher humidities. Usually equilibration was slower with aged tapes and was particularly slow when excess water was desorbing. This is reflected in the longer bars through the symbols,1.e. the tapes were further from equilibrium. 3.5